JERUSALEM – A Palestinian suicide bomber detonated a nail-studded device near a passing bus yesterday, an incident that puts further pressure on Prime Minister Ariel Sharon to deliver on his pledge to make Israel safe again.

The attack, which killed the bomber and injured more than two dozen bystanders, came just six hours after a car bomb exploded in a commercial section of Jerusalem, slightly injuring three people.

The blasts followed Monday’s killing of a 10-month-old Israeli girl by Palestinians. Last night, an 11-year-old Palestinian boy was killed during a clash with Israeli soldiers in the West Bank city of Hebron.

The prime minister has blamed the blasts on Palestinian leader Yasser Arafat, charging that “most of the terror attacks are done by forces under [his] command.”

But while vowing that the perpetrators would “not escape punishment,” he appeared to adopt a policy of restraint, shrugging off hard-line lawmakers who urged him to order a retaliatory strike.

In the evening, Sharon spoke with President Bush and condemned Arafat.

“The prime minister told President Bush that Arafat has refrained from ordering a halt to the terror … While Israel is taking a number of measures for easing up restrictions on the Palestinians, Arafat has taken advantage of this and not only has not halted the violence, but has even increased it,” Sharon’s office said in a statement.

“We look to the Palestinian Authority to do all it can to fight terrorism,” he said. “It can do such things like pre-empting attacks, arresting people who are responsible and bringing them to justice.”

In the suicide bombing, a Palestinian waited at a major intersection in northern Jerusalem and detonated a bomb strapped to his waist when a double-length bus passed by.

The bomber was torn to pieces.

The blast sent flames shooting up the side of the bus and blew out back windows.

“I saw a person cut in two, a body and a head lying in the street,” said witness Danny Sarero, 35.

Six hours earlier, a car bomb exploded in Talpiot, a crowded commercial area of outlets, wedding halls and car-repair shops in southern Jerusalem. Three passengers in a bus passing by at the time were slightly hurt.